Gemological investigation of azurite and malachite minerals in the Musalı (Mersin) region and their evaluation as ornamental stones

The malachite and azurite minerals found near Musalı village, located in the northwest of Mersin province, are in the Mersin ophiolite, which was tectonically deposited in the Upper Cretaceous. The majority of the Mersin ophiolite is composed of large serpentinized slices of harzburgite and tholeiitic diabase dykes cutting these slices as well as occasional dunite, harzburgite, and ortho pyroxenite bands. Quarries operating chromium ore were found in the ophiolitic units in the region, but no studies were found to have investigated copper mineralization. However, the presence of malachite and azurite also indicates the probable presence of copper mineralization in the region. Field surveys in the region showed that malachite and azurite minerals are predominantly present in cracks and pore spaces, mostly appearing as vein-like formations on the surface of the rocks. Azurite (Cu3(CO3)2(OH)2), a blue copper carbonate mineral, and its pseudomorph malachite (Cu2(CO3)(OH)2) usually occur at shallow depths in the oxidizing zone above copper deposits. The minerals azurite and malachite form as secondary minerals when slightly acidic, copper-bearing waters encounter a geochemical environment that allows carbonate minerals to precipitate as they percolate downward through cracks and pore spaces in the rock. Since azurite is often converted to malachite, they are found together in the same environment. Therefore, in this thesis, this dual copper mineral is referred to as azurmalachite. Bright-thin section examinations, XRD, XRF, and ICP-MS analyses were performed on azurmalachite and side rocks taken from the study field. According to the bright-thin section analyses and XRD results, the samples were found to have pyrite, chalcopyrite, azurite, malachite, pyroxene, and amphibole minerals. XRF analyses showed that Al2O3, CaO, Cu, Fe2O3, S and SiO2 values were high. According to ICP-MS results, Cu, V, Cr, Sr, Ni, Co ppm values were high. This study on the mineralogical-gemological analysis of azurmalachites in the region and their use as ornamental stones was funded by Mersin University BAP unit (project no: 2021-1-TP2-4291).